There is known a container lid which can be opened by a pull tab. While this type of lid has mainly been used as the lid of a can holding a beverage, it has also come to be used for a can holding food which is usually of the type which can be opened fully or across the whole area of its lid. In either event, this type of lid has the advantage of being openable more easily and safely than the lid of any can of the conventional type which requires a can opener. However, an opening made by tearing off a lid portion along a tear line forms a sharp edge which is very likely to hurt the fingers or hands of the person who opens the can or touches it thereafter.
Therefore, various attempts have been made to obtain a safer container lid construction. Reference is made by way of example to Japanese Patent Publication No. 44077/1972 for the invention entitled "Metal Container Lid and a Method of Making the Same" and U.S. Pat. No. 4,565,298 for the invention entitled "Safe Opening Container Lid". They propose the container lids which can form an opening having a safe edge.
U.S. Pat. No. 4,397,402 is directed to the invention entitled "Easily Openable Container Lid38 . It discloses a lid which can not only form an opening having a safe edge, but can also form a safe edge about its portion which is removed to make the opening. However, it has no tear tab, but its removable portion is surrounded by a groove in which a piece of hard material can be inserted to raise the removable portion and remove it. It can be formed from a sheet of material having a relatively high degree of ductility, but is difficult to form from a sheet of iron.
Under these circumstances, it is an object of this invention to provide a container lid having a removable portion which presents a safe edge when torn off along a tear line to form an opening in the lid.
It is another object of this invention to provide a container lid having only a low pop value and a low tear value so that, when a tab is raised to tear off its removable portion along a tear line, it may require only a small amount of force and be torn off very easily and safely.